1. Field of the Invention
The present invention relates to a printing apparatus that performs printing by ejecting droplets from a print head.
2. Description of the Related Art
Inkjet printing apparatuses include a print head having ink ejection orifices (hereinafter also referred to as nozzles) configured to eject a recording ink. When inkjet printing apparatuses eject an ink, the ink may adhere to a portion around the ink ejection orifices and may prevent a subsequent portion of ink from being properly ejected. Examples of such inkjet printing apparatuses include one that uses a reactive ink or a combination of a reactant and an ink and one that solidifies an ink with ultraviolet rays, microwaves, or heat to improve the fastness properties of the ink. In these inkjet printing apparatuses, an ink is more likely to be prevented from being properly ejected, thereby making it difficult to solve the problem of defective ejection. In order to solve the above problems, various methods of cleaning the surface of the print head on which the ejection orifices are formed (hereinafter also referred to as an orifice face) have been developed for inkjet printing apparatuses.
In order to prevent an ink from adhering to the orifice face of the print head and causing defective ejection, typical inkjet printing apparatuses include a member called a wiper that wipes the orifice face. The wiper wipes (performs a wiping operation) an ink adhering to the orifice face at an appropriate timing. The timing at which the wiper performs the wiping operation is determined, for example, by using a count of the number of times the print head ejects an ink (dot counting) and a timer in combination. In another example, the timing at which the wiper performs a wiping operation is determined by using normal dot-counting and printing duty.
The ink wiping proficiency may deteriorate in the following cases: the case where the ink adhering to the orifice face increases its viscosity due to evaporation of an ink solvent; and the case where a wiping operation cannot be performed for a long time due to the print head being heated to a high temperature or due to a long time being taken to perform printing. To address the above cases, a wiping operation may be performed after a wiper liquid containing at least one of an ink, an undiluted solvent, and a solution of the solvent is caused to adhere to the wiper (Japanese Patent Laid-Open No. 2003-300329).
Recently, a type of inkjet printing apparatus in which an ink adhering to a print medium is heated so as to be fixed to the print medium has been developed. In the inkjet printing apparatus according to Japanese Patent Laid-Open No. 2003-300329, an ink that has adhered to the orifice face is wiped by a sheet-form member serving as a cleaning unit instead of a wiper. A portion of the sheet-form member is used to clean the orifice face and then a predetermined length of the sheet-form member is wound so that an unused portion of the sheet-form member comes into contact with the orifice face of the print head in subsequent cleaning.
However, if, as in the case of Japanese Patent Laid-Open No. 2003-300329, the inkjet printing apparatus is controlled such that a predetermined length of the sheet-form member is wound every time after use, a length longer than necessary may be wound, and thus the sheet-form member may be wasted.